Ships, troops, and vehicles in combat situations attempt to hide themselves from the enemy as they manuever and prepare for battle. Ships and vehicles burn a rich fuel or fog oil that emits clouds of smoke. Troops have smoke grenades that emit smoke when ignited or fired. Fogging machines are also used in agriculture for spraying various chemicals to fulfill their various functions of covering and/or hiding objects. Usually the ingredients are liquid in nature and thus are relatively easily mixed and propelled into the atmosphere.